I am currently working with an architect to design a custom home including a basement home theater. I'm trying to decide on the most cost effective method of controlling noise transmission between the theater and the rest of the house. The house will be built using ICF (Insulated Concrete Forms). For the basement this basically means 2.5" of foam insulation on either side of an 8" concrete core.

In the photo below the hashed walls are the ICF walls basically surrounding the theater on most of three sides with concrete and earth. The other walls will most likely be staggered stud walls.

My biggest concern is sound transmission from the hardwood floors above and to a lesser extent the sound escaping the theater through the ceiling.

I've done my research read about sound proofing ceilings using all kinds of crazy techniques and about using under-laments like Serenity Mat under the floor above.

I can do either or both but which option is the most cost effective? Treat the floor or treat the ceiling?

Will a floor treatment (like Serenity Mat) help with sound escaping from the theater or just help deaden the foot-falls from above?

How would using a floor solution by itself compare with the various ceiling sound proofing options found here:

•Will a floor treatment (like Serenity Mat) help with sound escaping from the theater or just help deaden the foot-falls from above?

Serenity Mat will reduce, if not eliminate, foot fall noise from the hardwood floor above; however, its ability to reduce sound from the theater will be diminished by flanking through the joist cavities between the top of the ceiling and the subfloor above.

Quote:

•On a side note to avoid flanking through the side walls I wonder if any decoupling would be provided when attaching drywall to the furring strips in foam insulation of the concrete walls?

No. The foam insulation is rigid and will create a flanking path.

You have other issues you need to review with respect to your theater. These include placing the rear seats against the back wall (not at all a good practice) and your screen position. As currently designed, you'll have to place your center channel speaker above the screen in order to have line of sight to all the seats. Better to bring the screen forward and place the center behind an acoustically transparent screen. You do not need to have that single step behind the front row of seats ... it serves no function other than consuming floor space. It would also appear the intent is to pour the raised portion of the theater (behind the first row) in concrete. That is a very poor idea. It prevents the use of the raised platform for bass treatments and, if your viewing angle or seating distances are incorrect at this point, you'll have to live with it. While I'd agree the entrance design is cool, again it is a waste of limited floor space. The seating illustrated appears to be love seats and sofas ... that's quite OK; but, if you really intend to use recliners you'll need to examine the distance between seating rows.

I am currently working with an architect to design a custom home including a basement home theater. I'm trying to decide on the most cost effective method of controlling noise transmission between the theater and the rest of the house. The house will be built using ICF (Insulated Concrete Forms). For the basement this basically means 2.5" of foam insulation on either side of an 8" concrete core.

ohhh... I wonder if I could use green glue between the forms and the first layer of drywall? Wonder what green glue would do to the polystyrene of the forms?

Best case is it will offer zero soundproofing benefit, for a constrained dampening layer to be effective it needs to be between two rigid materials.
Worst case is it would dissolve the forms and the walls would fall down.

You need to frame frestanding walls in front of the forms attaching the top plates with IB3 isolation clips. Then use a clip and channel system for the walls and ceiling. Double layers of drywall with Green Glue.

You might be able to attach whisper clips to the furring in the foam, but talk to Ted it is not clear at all how robust the furring strips are and what weight load they can handle. They are also not visible in the picture you posted. I see foam ribs, put no wood or metal furring.

I was under the impression that walls adjacent to the foundation were decoupled (as long as the top plate was isolated with IB3 clips). Does this not apply when rigid foam is put up against the foundation? I hadn't planned on needing to do clips on the walls against the foundation.

Best case is it will offer zero soundproofing benefit, for a constrained dampening layer to be effective it needs to be between two rigid materials.
Worst case is it would dissolve the forms and the walls would fall down.

You need to frame frestanding walls in front of the forms attaching the top plates with IB3 isolation clips. Then use a clip and channel system for the walls and ceiling. Double layers of drywall with Green Glue.

You might be able to attach whisper clips to the furring in the foam, but talk to Ted it is not clear at all how robust the furring strips are and what weight load they can handle. They are also not visible in the picture you posted. I see foam ribs, put no wood or metal furring.

Sorry but if you want sound isolation your theater just got smaller.

I was hoping to avoid studding out the side walls. I want this room to have an open feel and keep my walkways close to 3' wide. The "furring strips" are actually extensions of the reinforced plastic ribs that hold the two sides of the form together. They end 1/2 an inch below the surface of the foam and have sections rated for 400 lb pullout (similar to a 2x4). I shouldn't have any issues attaching traditional double drywall and green glue combo to the forms (no green glue against the forms).

If I was going to give up width for stud walls on both sides I guess I could do the whole room within a room thing, I have the ceiling height. I'm not sure I would take it that far though if I could solve my primary concern by using something like Serenity Mat under the floors above.

Quote:

Originally Posted by Dennis Erskine

Serenity Mat will reduce, if not eliminate, foot fall noise from the hardwood floor above; however, its ability to reduce sound from the theater will be diminished by flanking through the joist cavities between the top of the ceiling and the subfloor above.
No. The foam insulation is rigid and will create a flanking path.

You have other issues you need to review with respect to your theater. These include placing the rear seats against the back wall (not at all a good practice) and your screen position. As currently designed, you'll have to place your center channel speaker above the screen in order to have line of sight to all the seats. Better to bring the screen forward and place the center behind an acoustically transparent screen. You do not need to have that single step behind the front row of seats ... it serves no function other than consuming floor space. It would also appear the intent is to pour the raised portion of the theater (behind the first row) in concrete. That is a very poor idea. It prevents the use of the raised platform for bass treatments and, if your viewing angle or seating distances are incorrect at this point, you'll have to live with it. While I'd agree the entrance design is cool, again it is a waste of limited floor space. The seating illustrated appears to be love seats and sofas ... that's quite OK; but, if you really intend to use recliners you'll need to examine the distance between seating rows.

Food for thought.

Sorry about the rough sketch the "loveseats" are just representations, visio has limited furniture options First two rows will be theater seats with about 6' 10" to contain the reclining second row. The back seats will not be recliners just comfy gaming seats and at most "overflow" theater seating. I'm ok with them being out of the optimal sound envelope. as long as I can get 7-8 "good seats" in the fist two rows. I do as much xbox and PC gaming in there as I do movie watching.

As for the riser most of the section of the theater that is surrounded by the ICF walls will be one form (16") deeper than the rest of the basement. So i'll end up putting a wood riser to support the entire second row while getting over 10.5' feet of height at the front. There will actually be a second wood riser under the 3rd row of seats. I will most likely at least stud out the front wall so I can get a good quality in-wall center channel behind the screen.

I was under the impression that walls adjacent to the foundation were decoupled (as long as the top plate was isolated with IB3 clips). Does this not apply when rigid foam is put up against the foundation? I hadn't planned on needing to do clips on the walls against the foundation.

I think you are correct? If you decouple your studded walls next to your foundation walls and use clips or some other method of decoupling on the ceiling I wouldn't think any additional decoupling would be necessary on the walls.

I was asking about applying the drywall directly to my ICF walls, in which case (as Dennis pointed out) the foam would be a rigid surface not allowing for any decoupling.

I'll have to play with my design and see how much space I am willing to give up. I have to decide if I am willing to give up the space required to properly do the decoupling or if I can live with adding mass and dampening elements.

IF I'm reading your room dimensions right, giving up 6" inches on a 15'6" wide room should be the LEAST of your design problems. I'd KILL for the extra 3' you have over my room.

I know, I know... my current theater is only 11' wide at the front. But with this one I wanted to be able to do 4 theater seats across AND keep 3' isles on each side. Going for an open feel and clean look.

Looking at the revised picture you MIGHT be able to mount something like a Whisper clip to the furring. What is the furring made of and how is it secured to the structure? That would save the need to frame additional walls.

The furring strips are High-density, Molded Plastic Webs spaced every 6" horizontally. Once the wall is done the center of those webs are embedded in an 8" core of concrete and rebar and they extend through foam insulation on each side providing the furring strips and attachment points 1/2" below the surface of the foam on both the exterior wall and the interior.

Additionally there are "Heavy-duty Attachment Points (450lbs.+). Located every 8" vertically and every 6" horizontally, allowing for secure attachment of bracing or heavy cabinetry."

I've seen almost every type of siding attached to these on the exterior and cabinets, stud walls and drywall on the interior.

With the furring sitting 1/2 inch below the surface of the foam I would think that just about any clip would deform the foam under a weight load. I think I would be tempted to first mount a 6 inch vertical strip of 1/2 inch thick Hardwood plywood both Glued and screwed at each furring strip location. That would give a larger base for the clips to distribute the load and I think you could proceed as usual. Just a theory not a proven technique. Ted White at soundproofingcompany.com may have encountered a client with this type of foundation wall and it would be worth a call. The clip screws should extend through the furring.

With the furring sitting 1/2 inch below the surface of the foam I would think that just about any clip would deform the foam under a weight load. I think I would be tempted to first mount a 6 inch vertical strip of 1/2 inch thick Hardwood plywood both Glued and screwed at each furring strip location. That would give a larger base for the clips to distribute the load and I think you could proceed as usual. Just a theory not a proven technique. Ted White at soundproofingcompany.com may have encountered a client with this type of foundation wall and it would be worth a call. The clip screws should extend through the furring.

Thats a good point Big. Every thing else I have seen attached to the forms had the load on the foam spread over a wider area where by design the clips would be concentrating that load somewhat. There are a couple other places I might use that technique too... Thanks!

I'll go ahead and post the other design I am considering since my thread in the General Home Theater forum isn't getting much love.

Design 4: The front of the theater will be the same as Design 1 but it gives up the double entry and splits the gaming area into two separate sections. Allows for more creative "game station" setups and potentially more overflow seating. Gives up the cool double entry though.

Back to design 1, with the double entry, If you wanted a better surround sound field for the rear row you could make the wall behind the third row only as tall as the back of the seats, put a door in the single entry point and hang the speakers on the back wall.

If you are doing a true Room in a Room design. IE - none of the interior walls or ceiling are coupled to any of the exterior walls & ceiling, why would there be any reason to also use clips?
You have already decoupled everything by doing the room in a room. Haven't you?

I picked up this pic from an other thread and marked it up for an example.

OK I may be over thinking this but here we go. Dimensions have changed slightly from initial posts so I am considering a room-within-a-room design.

The current sound containment plan would include

Stud walls all the way around the theater placed 1/2" - 1" away from all surrounding walls and ending 2" below the level of the floor joists above.

Ceiling Joists interleaved with the floor joists above resting on the decoupled stud walls about 2" below the level of the floor joists

OSB > Green Glue > Drywall on all interior surfaces giving me my "shell". All soffits and columns will be built inside this shell.

All lighting, outlet boxes, in-wall speakers and low voltage penetrations will be in the soffit or columns inside of the shell.

Penetrations through the shell will include, HVAC Supply, HVAC Return, Main Door and low voltage/electrical wiring.

I will include the EQ room as part of the sound containment envelope.

Rough Plan

SketchUp Top

SketchUp Top Anfled

ICF

Floor Ledger

In the last 2 pics I am trying to detail the floor ledger attachment methods and over all ICF construction because the details are different than traditional construction. The basement and both levels above are ICF construction. 8" of concrete on the basement level and 6" on the 1st and 2nd floors surrounded by 2.5" of foam on each side. The flanking paths are different that traditional construction.

Decoupling the ceiling makes sense.
Decoupling the rear wall and the part of the side walls not adjacent to the foundation makes since.
Am I really getting any benefit from placing decoupled walls in front of my foundation walls?
What I am trying to figure out is am I wasting 8" of room width for very little gain?